Process for screening cathode ray tubes including salvaging of excess phosphor slurry

ABSTRACT

A PROCESS FOR MAKING A PHOSPHOR SCREEN FOR A CATHODE RAY TUBE HAVING A FACEPLATE PANEL WHICH IS IN ONE OF A PLURALITY OF SIZE RANGES. FIRST, A QUANTITY OF PHOSPHOR SLURRY IN EXCESS TO THAT REQUIRED FOR THE SCREEN IS DISPENSED INTO THE PANEL. THE SIZE RANGE OF THE PANEL IS SENSED AND A SLURRY COLLECTOR MEANS OF THE PROPER SIZE IS SELECTED FROM A PLURALITY OF SUCH COLLECTOR MEANS AND MOVED INTO A SALVAGE POSITION WITH RESPECT TO THE PANEL. THE PHOSPHOR SLURRY IS SPREAD OVER THE INNER SURFACES OF THE PANEL AND THE PANEL IS SPUN TO FLING THE EXCESS SLURRY THEREFROM INTO SAID SLURRY COLLECTION MEANS. THEN, THE EXCESS SLURRY IS RECOVERED FROM THE SLURRY COLLECTION MEANS.

J1me 1972 F. T. D'AUGUSTINE 3,672, 3

PROCESS FOR SCREENING CATHODE RAY TUBES INCLUDING SALVAGING OF EXCESS PHOSPHQR SLURRY 1 Filed June 24, 1969 2 Sheets-Sheet 1 250 50 Fig 1 59 25b 2 26b 240 53/ I 444 5O 3* 37 t 45 56 A 35 53c 58 59 9 55 a 28 ""36 59 42 INVENTOR. Frank Thomas D'Augusfine ATTORNEY June 27, 1972 F. T. DAUGUSTINE 3,67

PROCESS FOR SCREENING CATHODE RAY TUBES INCLUDING SALVAGING OF EXCESS PHOSPHOR SLURRY Filed June 24, 1969 2, Sheets-Sheet 2 l9" -uw 35 53C 40 5 i 36 g 34 E 3| M UNLOAD LOAD UNLOAD /LOAD 49 [II D CI EI EI 4 um I3 21 QIQ 46c panama? V |i1|i|c| 490 46d 49d LOAD 470 45 UNLOAD- INVENTOR. 3 Frank Thomas D'Augusfine ATTORNEY United States Patent US. Cl. 117-335 C 2 Claims ABSTRACT OF THE DISCLOSURE A process for making a phosphor screen for a cathode ray tube having a faceplate panel which is in one of a plurality of size ranges. First, a quantity of phosphor slurry in excess to that required for the screen is dispensed into the panel. The size range of the panel is sensed and a slurry collector means of the proper size is selected from a plurality of such collector means and moved into a salvage position with respect to the panel. The phosphor slurry is spread over the inner surfaces of the panel and the panel is spun to fling the excess slurry therefrom into said slurry collection means. Then, the excess slurry is recovered from the slurry collection means.

BACKGROUND OF THE INVENTION This invention relates to a novel surry process for preparing phosphor screens for cathode ray tube faceplate panels including salvaging excess slurry from the panel.

In some prior slurry processes for making a phosphor screen, an excess of phosphor slurry is dispensed into a panel and the panel rotated to spread the slurry over the panel and throw excess slurry from the panel into a collection means. The collected slurry is then removed from the collector means by draining and subsequently reused in screening another faceplate panel.

These prior processes are useful, at present, for processing a succession of faceplate panels all of which are of the same or almost the same panel size. It is desirable to improve these prior processes so that an intermixed range of widely differing panel sizes can be processed sequentially in random size order.

SUMMARY OF THE INVENTION In the novel slurry process for making a phosphor screen for a cathode ray tube, the faceplate panel may have any panel size within a range of panel sizes. In the process, a quantity of phosphor slurry in excess of that required for the screen is dispensed into the panel. The size range of the panel is sensed and the proper size slurry collector means is selected from a plurality of collector means of different size ranges. The selected collector means is moved into a salvage position with respect to the panel. The panel is rotated so as to spread the phosphor slurry over the inner surface of the panel and to fling the excess slurry therefrom into the slurry collection means. The excess slurry is collected from the collector means.

By sensing the size of the faceplate panel and by selecting the proper size collection means from a plurality of collection means of different size ranges, the novel process permits a plurality of panel sizes, some of which may differ widely in size, to be processed in series in any size order thereby providing the economy of high production rates when lower outputs of several sizes are desired.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional side elevational view of a slurry salvage station including a preferred embodiment of the 3,672,932 Patented June 27, 1972 invention in position for salvaging slurry from a smaller size panel.

FIG. 2 is a sectional elevational view of the embodiment of FIG. 1 in position for salvaging slurry from a larger size panel.

FIG. 3 is a schematic plan vie-w of a continuous type slurry screening machine containing three phosphor salvage stations, each including the embodiment of FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus in FIG. 1 and FIG. 2 includes two slurry collection pans 22 and 23 of graduated sizes positioned nested one-inside-the-other. The smaller size collection pan 22 is used to collect slurry from 17 inch panels 24a (phantom line) and 19 inch panels 24b (solid line) as shown in FIG. 1, and the larger size collection pan 23 is used to collect slurry from 22 inch panels 240 (phantom line) and 25 inch panels 24d (solid line) as shown in FIG. 2. The panel is mounted on a work holder 50 and held in position by clamp 51 as will be described in detail below.

The smaller size collection pan 22 has a cylindrical sidewall 25a with an inside upturned lip 26a on its lower edge and a spout 27a opening from the lip 26a. The larger size collection pan 23 also has a cylindrical sidewall 25b with an inside upturned lip 26b on its lower edge and a spout 27b opening from the lip 26b. When the two pans 22 and 23 are positioned one-inside-the-other, the spouts 27a and 27b are positioned in series with the spout 27a of the smaller size pan 22 opening into the spout 27b of the larger size pan 23. A funnel 28 is positioned to enclose the opening of the spout 27b of the larger pan at all times. A drain hose 29 is connected to the funnel 28.

The larger size pan 23 is attached to one end of a support bracket 30b which is mounted on a pivot shaft 32 in the pan support frame 31. A crank arm 33 is attached to the other end of the support bracket 30b as shown. A first pneumatic cylinder 34 is connected between a pivot shaft 35 on the crank arm 33 and a pivot shaft 36 on the frame 31. When the first pneumatic cylinder 34 in the extended position as shown in FIG. 2, the larger size pan 23 is down, in the salvage position over the panel. The smaller size pan 22 is attached to one end of a second support bracket 30a. This support bracket 30a similarly mounts on the same pivot shaft 32 in the pan support frame 31. The pivot shaft 32 is so positioned that the smaller size pan 22 can rotate about the pivot shaft 32 and still retain the opening of the spout 27a inside the sidewall 25b and spout 27b of the larger size pan 23 when the smaller size pan 22 is in either of the extreme positions up or down as shown in FIG. 1 and FIG. 2.

The collection pans 22 and 23 are normally positioned in the up or standby position at an angle of approximately 45 from the horizontal with the spouts at the lower side, and are mounted to pivotally rotate to a salvage position over the panel to an angle of approximately 30 from the horizontal. When the two pans 22 and 23 are positioned nested one-inside-the-other, the support bracket 30a for the smaller size pan 22 is against and supported by the support bracket 30b of the larger size pan 23 as shown in FIG. 1. The support bracket 30a of the smaller size pan 22 includes a lever 37 with a latch catch 38. A latch lever 39 is clamped on the pivot shaft 40 in the frame 31. The latch lever 39 is shaped at one end to engage the latch catch 38 when the smaller size pan 22 is in the position shown in FIG. 2. A connecting lever 41 is also clamped to the pivot shaft 40 at one end of the connecting lever 41. The other end of the connecting lever 41 has a slot therein. The piston of a second pneumatic cylinder 42 is pivotally linked through the slot with a sliding pivot pin 43. The

second pneumatic cylinder 42 is mounted on the frame 31 and attaches to the connecting lever 41 at the sliding pivot pin 43. With the second pneumatic cylinder 42 in the extended position, the latch lever 39 is engaged with the latch catch 38 with the smaller size pan 22 in the position as shown in FIG. 2.

The continuous slurry screening machine, schematically shown in plan view in FIG. 3, is one type which can use the salvage station embodiment shown in FIG. 1 and FIG. 2. The machine in FIG. 3 includes two endless loop conveyors each comprised of a plurality of panel carriers 45 which are indexed through a multiple number of phosphor processing stations. The machine also includes four load stations 46a, 46b, 46c and 46d, three phosphor slurry dispense stations 47a, 47b and 47c, three "slurry salvage stations 48a, 48b and 480 of the embodiment of FIG. 1 and FIG. 2, and four unload stations 49a, 49b, 49c and 49d.

Referring again to FIGS. 1 and 2, a rotatable work holder 50 is mounted on each of the plurality of panel carriers 45 which are rollably mounted on a stationary carrier support 44 on rollers 59. The rotatable work holder 50 may be dilferent for each of the four panel sizes which are normally processed. A clamping means 51 is mounted on the work holder 50 to hold the particular panel size. A flag type actuator 52a, 52b or 52c is positioned on the side of each carrier 45 facing the carrier support 44 in a discrete position as related to a 17 inch, a 19 inch or a 22 inch panel on the carrier 45. No flag is used for processing a 25 inch panel 24d. At each salvage station 48a, 48b or 480, three switches 53a, 53b and 530 are positioned on the conveyor frame 44 to be contacted by either the flag 52a, 52b or 520 asthe carrier 45 moves into the salvage station 48a, 48b or 480.

In 'FIG. 1 and FIG. 2, a gearmotor 55 is mounted in the frame 31 at the salvage stations 48a, 48b and 470. LA friction drive wheel 56 on the gearmotor 55 drives a driven wheel 57 on the carrier 45 to turn the rotatable work holder 50. A means (not shown) is also used to tilt the panel and the rotatable work holder 50 about a pivot point 58 to position the driven wheel 57 in proper contact with the drive wheel 56 and to obtain the different angular positions of the rotatable work holder required at each of the other multiple number of processing stations.

In using the continuous slurry screening machine of FIG. 3, a panel of the proper size is loaded on the carrier in a load station 46a, 46b or 46c. The carrier 45 moves to a slurry dispense station 47a, 47b or 47c where a quantity of slurry in excess of that required to make a phosphor coating is dispensed. The carrier 45 then moves to a salvage station 48a 48b or 480 where the excess slurry is salvaged. Then, the carrier 45 moves to an unload station 49a, 49b or 49c where the panel is unloaded for exposure of hte phosphor coating. After unloading the panel at each of stations 49a, 49b and 49c, the panel is exposed to a light image in a lighthouse (not shown). In FIG. 3, two loop conveyors, each comprised of a plurality of panel carriers 45, are used to make the phosphor screen for a color television picture tube requiring repeating a slurry process for each of three color phosphors. The stations 46a through 49a are for applying green phosphor slurry, 46b through 49b are for developing the green phosphor pattern and for applying blue phosphor slurry, and 460 through 490 are for developing the blue phosphor pattern and for applying red phosphor slurry. The stations 46d through 49d are for developing the red phosphor pattern and for applying an organic film to the phosphor coatings.

In using the phosphor salvage apparatus shown in FIG. 1 and FIG. 2, a carrier 45 containing a panel into which a quantity of phosphor slurry has been previously dispensed, for example, at slurry dispense station 47a, is moved into slurry salvage station 48a. A tilting means (not shown) moves the rotatable work holder 50 about a pivot point 58 to engage the carrier driven wheel 57 with the friction drive wheel 56. As the carrier 45 is moved to the salvage station 48a, the size of the panel on the carrier is detected, and the flag type actuator selects the proper collection pan and the prescribed program of panel rotation speeds and time duration at each speed. In operation, the machine cycle control automatically selects a pan having the correct size and the prescribed program for the panel in the carrier. Each carrier has either no flag or one discretely positioned flag- 52a, 52b or 52c on the carrier frame 45. Either none or one of three switches 53a, 53b or 530 is actuated at the salvage position by the flag. The discrete position of the flag 52a, 52b or 52c relates to the size of the 'panelon the carrier. With no switch actuated, the collection pan and program for a 25 inch panel are selected. A flag 52a on a carrier holding a 22 inch panel 24c actuates a switch 53a to cancel the automatically prescribed program for a 25 inch panel 24d and selects the rotational program for a 22 inch panel 240. The large size pan 23 is used for both the 22 inch panel 240 and for the 25 inch panel 24d. A flag 52b on a carrier holding a 17 inch panel 24a actuates a switch 53b to cancel the prescribed program for the 25 inch panel 24d and to select a prescribed program for the 17 inch panel 24a. This switch 53b also selects the small size pan 22 in addition to the large size pan 23 (both pans 22 and 23 are used). A flag 52c on a carrier holding a 19 inch panel 24b actuates a switch 530 to cancel the prescribed program for the 25 inch panel 24d and to select the prescribed program for the. 19 inch panel 24b. In addition, this switch 53c selects the small size pan 22 in addition to the large size pan 23. (both pans are used). The pan selection is carried out in the following manner. When a carrier holding a 22 inch .panel 240 or a 25 inch panel 24d is moved into the salvage position, the latch lever 39 is engaged with the latch catch 38 holding the small size pan 22 in the up position, and the first pneumatic cylinder 34 is operated to lower only the large size collection pan 23 to a salvage position over the panel. When a carrier holding either a 17 inch panel 24a or a 19 inch panel 24b is moved into the salvage station, the second pneumatic cylinder 42 is operated to pivot the latch lever 39 away from the latch catch 38 of the small size pan 22, and the first pneumatic cylinder 34 is operated to lower only the larger size collection pan 23 to a salvage position over the panel. The flags 52a, 52b and 520 are also used for process control of intermixed panel sizes at other stations of the continuous slurry machine shown in FIG. 3. v

The use of only the first pneumatic cylinder 34 to lower both pans 22 and 23 and the resting of the support bracket 30a of the smaller pan 22 on the support bracket 30b of the larger pan ensures that when both pans are required they are lowered together. After the collection pan 23 or collection pans 22 and 23 are in a salvage position over the panel, the gear-motor 55 drives the friction wheel 56 according to the prescribed program to turn the driven wheel 57 on the carrier 45 and rotate the panel on its central axis. This serves to spread the slurry over the inside surface of the panel and to throw the excess slurry onto the inside sidewall 25a or 25b of the collection pan 22 or 23 directly surrounding the panel. For a larger size 22 inch panel 240 or 25 inch panel 24d, the slurry is caught on the sidewall 25b of the larger size pan 23 and flows by gravity into the lower lip 26b, around the lip 26b into a spout 27b and from the spout 27b into a funnel 28 positioned on the frame 31 below the spout 27b. The collected excess slurry flows from the funnel 28 into a drain hose 29 to return it to the slurry supply for subsequent reuse in screening other panels. For a smaller size 17 inch panel 24a or 19 inch panel 24b the slurry is caught on the sidewall 25a of the smaller pan 22 and flows by gravity into the lower lip 26a, around the lip 26a into a spout 27a, and from the spout 27a to the spout 27b in the larger size pan 3, and from the spout 27b into the same funnel 28. The use of a funnel 28 permits the larger size pan 23 to drain when over the panel and when away from the panel and permits quick removal of the pan for cleaning as required. After the slurry is collected, the rotational speed of the panel is reduced and the collection pan or pans are moved away from the panel permitting the panel to advance to the next station. The slurry which has not drained from the collection pans can continue draining by gravity into the funnel 28. The conveyor then moves this carrier containing the panel from which the slurry has been salvaged to the next processing station, and moves the succeeding carrier carrying another panel which may be different in size into the slurry salvage station.

In one typical practice of the novel process using the continuous screening apparatus of FIG. 3, excess phosphor slurry may be salvaged from an intermix of 19 inch, 22 inch and 25 inch color television panels in the following manner. A carrier 45 holding one of above panel sizes is moved from a dispense station 47a (or 47b or 470) to an adjacent salvage station 48a (or 48b or 480). The work holder 50 on this carrier is positioned to hold the axis of rotation of the panel tilted about 30 from the vertical and to engage the friction drive wheel 56 with the carrier driven wheel 57 at the salvage station 48a (or 48b or 480). Prior to moving the panel into the salvage station, an approximate quantity of green, blue, or red slurry as listed in the table is dispensed into the panel at the dispense station 47a, 47b or 47c to make the phosphor pattern. As the carrier moves into the salvage station, the flag 52a, 52b or 520 which is discretely positioned on the carrier to relate to the panel size on the carrier actuates none or one of three switches 53a, 53b or 530 at the salvage station 48a, 48b or 480 to select the proper collection pan 22 or 23 or pans 22 and 23 and the prescribed program to rotate the panel on the carrier 45 for collecting the excess slurry therefrom. The proper collection pan is moved into a slurry salvage position over the panel and each size panel is rotated about the speeds and corresponding time duration listed in the table to centrifugally throw the excess slurry from the panel into the salvage pan. The approximate quantity of slurry in excess of that required to make a phosphor screen (listed in the table) is collected in the salvage pan and returns to the slurry dispense position.

Comparing the quantity of slurry dispensed and the quantity of slurry salvaged as listed in the table, a much larger quantity of slurry is dispensed than is required to prepare the screen. The collection and reuse of this large quantity of excess slurry are necessary to provide economy of manufacture using the slurry process. After the prescribed panel rotation program is complete, the collection pan is moved from the panel and the conveyor indexes this carrier and panel to a succeeding processing position and indexes a succeeding carrier which may have a panel of a different size into the salvage position. The quantity of each difierent panel size processed on the continuous slurry machine can be selected by changing the size of the work holders on the machine. The flag on each carrier is then repositioned to correspond to the panel size of the selected work holder mounted on the carrier.

In processing an intermix of panel sizes on a continuous screening machine having 42 carriers and a 32 second index cycle, 100% utilization would screen about 1200 panels in an eight hour shift. An intermix of only two sizes using only one carrier for the first size and 41 carriers for the second size is possible and will permit screening at 100% utilization as small a quantity as 29 of the first size. The novel process permits small numbers of panel sizes to be screened by automated machines with the economy of automated production.

The salvage apparatus shown in FIG. 1 and FIG. 2 discloses nested pans. The novel process could be carried out with other arrangements. For example, pans of difierent sizes could be positioned in opposed positions or on a rotary turntable in such a manner that the proper size pan for a particular panel would move over the panel to collect the excess slurry.

In addition, the novel process may be carried out in a slurry machine in which the slurry dispense and salvage stations are combined into a single station by using a retractable dispense nozzle or a dispense nozzle mounted to operate with the salvage collection means. The embodiment may also be used on a single or dual position slurry screening apparatus where production needs are not sulficient to require a continuous screening apparatus.

TABLE Time P 1 duratloln A m t ane o pprox a e Approximate rotational rotational volume volume of speed speed of phosphor for for phosphor Panel slurry Phosphor phosphor slurry size, dispensed, salvage, salvage, salvaged, Phosphor slurry color inch cc. r.p.m. see, no

67 4% 113 51 Green phosphor slurry 22 99 67 6% a 2 I9 95 g? g 60 57 2 22 130 84 in 90 Blue phosphor slurry l 172 15 s2 19 100 gg 75 Red phosphor slurry 22 135 122 13 100 7 1. A process for phosphor screening cathode ray tube faceplate panels of difierent sizes comprising the steps of:

(a) passing said panels in series in random size order to a slurry salvtge position, then for each panel,

(b) dispensing into the panel a quantity of phosphor slurry in excess of that required to prepare a screen therefor,

(c) sensing the size range for said panel,

(d) selecting, in response to said sensing step, a slurry collection means of the proper size range from a plurality of graduated-sized, nested collection means,

(e) moving said selected collection means into a slurry salvage position closely spaced from and surrounding said panel,

(f) rotating said panel about its central axis to centrifugally flow the excess slurry therein toward the edges of said panel and to throw the excess slurry from said panel through space into said collection means,

(g) collecting the excess slurry so thrown from said panel in said collection mean,

(h) moving the collecting means out of the salvage position and away from said panel, and

(i) draining the collected excess slurry from said collection means.

2. A method according to claim 1 wherein said collection means includes at least two nested pans of graduated sizes positioned one-inside-the-other, with each pan having a sidewall with a lower lip and a spout opening at one point from said lip, and each pan mounted on a bracket with all brackets having a common pivot point which permits limited movement of each interior pan and maintains the spout of said interior pan inside the spout and sidewall of the next larger pan at all times, including the additional steps of:

(a) catching said excess slurry on the interior sidewall of one' of said collection means,

(b) flowing said excess slurry down said wall by gravity into said lip and around and down said lip into said spout,

(c) collecting said excess slurry from said spout of one of said collection means,

(d) draining said excess slurry in series through each spout of each of said pans of graduated sizes to the to the spout of the largest of said collection means, and

(e) collecting said excess slurry from the spout of the largest of said collection means..

References Cited UNITED STATES PATENTS 3,313,643 4/1967 Branin 117--102 R 3,364,054 1/ 1968 Weingarten 1l7102 R 3,376,153 4/1968 Fiore 1l7102 R 3,467,059 9/1969 Korner et a1. 1l7102 M. F. ESPOSITO, Assistant Examiner U.S Cl. X.R.

1l733.5 CM, 33.5 CS, 102 R 

